California sea hare

California sea hare

California sea hare

2 languages
Aplysia californica
2.3 kg
40 cm

The California sea hare (Aplysia californica ) is a species of sea slug in the sea hare family, Aplysiidae. It is found in the Pacific Ocean, off the coast of California in the United States and northwestern Mexico.


The maximum length recorded for the California sea hare is 75 cm (30 in) when crawling, thus fully extended, although most adult specimens are half this size or smaller. Adult animals can weigh up to 7 kg (15 lb). A closely related species, Aplysia vaccaria, the black sea hare, can grow to be larger still.



A. californica is found along the coast of California, United States, and northwestern Mexico (including the Gulf of California). Aplysia species inhabit the photic zone to graze on algae, mainly the intertidal, usually not deeper than 18–20 m (59–66 ft).

California sea hare habitat map

Climate zones

California sea hare habitat map
California sea hare
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Habits and Lifestyle

Like all sea hares, the California sea hare is hermaphroditic, acting as male and female simultaneously during mating. A. californica is known to form mating chains with up to 20 animals. The eggs are yellow-green, and change after 8–9 days into a brown color before larvae hatch. Mating is most prominent during the summer following the rise of the water temperature to 17 °C.

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A. californica has a generation time of 19 weeks: Days 1-37 after hatching from the egg comprise the planktonic stage, days 34-37 are the metamorphic stage, and days 45-80 are the juvenile stage. Reproductive maturity is reached 85 days after hatching (133 days after deposition of the fertilized eggs). The development of the nervous system lasts for 140 days The lifespan is assumed to be around a year, yet older animals have been found. Cooler temperatures delay spawning and has been shown to extend the lifespan.

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Seasonal behavior

Diet and Nutrition

Like all Aplysia species, the California sea hare is herbivorous. Its diet consists primarily of red algae such as Laurencia pacifica, Plocamium pacificum, and Ceramium eatonianum, which give the animal its typically reddish or pinkish coloration. A. californica resembles the food on which it grazes, and cannot be distinguished easily from the seaweed unless the animal is moving.

Mating Habits

10 to 12 days
80 million



1. California sea hare Wikipedia article -

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